check shift control then check engine warning

[scharebear]

Yesterday after coming off plane I got 'check shift control' warning and then 'check engine warning' immediately after. The motor was purring fine. Would not shift into forward or reverse. Turned of motor, shut off batteries, turned everything back on and all was good. Happened once more later in day but I did not see the check engine warning this time. Any thoughts as to what is causing this? I have not had it checked yet by mechanic but he is good with motor, not so good with electronics. I am anticipating "I wasn't able to reproduce the error." I think I know more than him about electronics from this forum.
It is single 2013 DF 300 about 180 hrs.

[scharebear]

I took it out again and same issues several times. Paid closer attention and noted that check engine warning had code 8-3 with it. Any thoughts? From google I have found the code is "ESA No" but I do not know what that is. Thanks.

[scharebear]

Problem solved.
The shift actuator at the engine had some corrosion and was sticking.
Has anyone else ever had this happen? Motor at 190 hrs now. Somehow salt-water got in there. Mechanic also noted that there is no grease there from factory and would likely prevent this.